Push-pull switch



Patented Nov. 30, 1943 PUSH-PULL SWITCH David W. Johnson, New Britain,Coma, assignor to The Arrow-Hart & Hegeman Electric 00., Harti'ord,Comm, a corporation of Connecticut Application July 11, 1941, Serial No.402,013

4 Claims.

This invention relates to electric switches. More particularly, itrelates to an electric switch in which certain contacts can bemomentarily engaged or disengaged by a push or pull applied to areciprocating member.

In the control of electric motors by solenoidoperated switches, it isoften necessary to employ in the control circuit switching means forcompleting and breaking the circuit to the solenoid. This has commonlybeen accomplished heretofore by the use of a device embodying two operating push buttons, one being for starting" or, in other words,completing a holding circuit, and the other being for stopping or, inother words, breaking the holding circuit. One disadvantage of this typeof control is that accidental pressure upon the starting button cancause closing of the main switch and possible starting of a motor orlarge piece of machinery. Another disadvantage of this type of controlis that two spaced operating buttons are required, which sometimesoccupy space on panel boards or other mountings wherein the amount ofspace is limited. Still another disadvantage of this type of control isthat the operator of a machine must look up from his work to see whichbutton he is pressing when he wants to stop the machine.

It is an object of my invention to provide a single switch which canaccomplish the functions of starting and stopping and which will be freeof the foregoing disadvantages of the prior type of control in therespect that the invention shall have only one operating member whichthe Other objects and advantages of my invention, in addition to thoseabove mentioned, will become apparent as the invention is described inconnection with the accompanying drawing.

In the drawing- Fig. l is a plan view of the invention;

Fig. 2 is a vertical mid-section view taken along line 2-2 of Fig. 1 ofthe invention, showing in full lines the parts in normal position, whilein dotted lines the parts are in stopping or pushed-in position.

Fig. 3 is a side elevation view partly broken away of the invention.

Fig. 4 is a bottom view of the invention.

Referring to the drawing, the active parts of the device are mounted ina base or block ID of molded insulating material which is provided inits top face with a cylindrical well or cavity [2 to receive acylindrical plunger or hand grip H. In order that the plunger I 4 may beeither pushed or pulled, its outer or upper end is recessed around itsperiphery as at Ma, to afford a grip for the fingers of a machineoperator, and its top surface is made fiat or slightly concave or covex,as preferred, to provide a surface for engagement by the thumb or palmof the hand of the operator. The inner or bottom end of the plunger iscylindrically recessed to provide a seat for a compression spring itbetween the plunger and the insulating body [0.

The base 10 beneath the plunger is provided with a circular aperture orpassage communicatmachine operator can actuate to start or stop" 4 byPulling or pushing.

Another object of my invention is to provide a switch which maymomentarily open or close one circuit, or more than one circuit bymomentary contact engagement or disengagement through actuation of asingle operating member.

Still another object oi my invention is to reduce the space and numberof devices and cost or installation of switching means which can be usedfor stopping and starting electric motors and the like.

Although the invention will be described as used in motor controlcircuits, it will be obvious that it may be applied generally to use inswitching-arrangements in a wide variety of applications.

ing with a recessed bottom portion of the base and admitting the passageof a spindle l8 on whose upper end the plunger I may be molded. The midportion of the spindle I8 is of reduced section providing a shoulder l8aagainst which normally is pressed a conductive bridging contact bar 20which is slidably mounted upon the spindle. The bridging bar has contactbuttons 22 and v24 mounted near its ends in position to engage withcontact buttons 26 and 28 that are mounted upon the end portions ofterminal bars 30 and 32. .These terminals 30 and 32 extend outwardly ofthe base, which is conveniently recessed for that purpose, and they areheld in position by bolts such as 34 extending through from the top ofthe base into threaded apertures in said terminals.

In order to hold the contact buttons of the bridging bar 20 inengagement with the contact buttons of the terminals 30 and 32, a coiledcompression spring 36 is placed around the reduced portion of thespindle I 8 in position to have one end of the spring press against theunder surface of the bridging bar 20. The other end of spring 36 seatsupon the flange or a collar 38 whichis slidably mounted upon the spindlel8 and rests upon the upper or inner surface of a second or lowerbridging bar 40 located at the lower end of the spindle. The bridgingbar All may be similar or identical in construction to the bar 20 andmay have its contact buttons 42 and ill in position to engage with thecontact buttons :36 and 48 on terminal bars 50 and 52. The terminals 50and 52 may be similar or identical to the terminals 30 and 32 but willpreferably an tend to the opposite side of the base "I from theterminals 30 and 32. The base is convenient- 1y recessed to provideledges such as 56 upon which the mid-portions of the terminals Ill-and62 may be secured by bolts, such as 54, extending upwardly through thebottom of the base and threading into threaded apertures in theterminals 50 and 52.

In order to hold the bridging bar 40 on the spindle, anginsulating disc60 and a metallic washer 62 may be held against the end of the spindleby the head of a screw 64 threaded into the spindle end; or in lieu ofthe screw 64, the

lower end of the spindle maybe further reduced in section and peenedover to form a permanent securing means for the .disc 60 and washer 62.

In order that the parts of the device may normally be maintained inposition of Figs. 2 and 3 wherein the contact buttons of upper bridgingbar it are in engagement with the contact buttons on the terminals 30and'32, the distance from the shoulder 58a to the insulating disc 60 isgreater than the distance from the surface of the stationary contactbuttons 26 and 28 to the surface of the contact buttons 46 and 48, andthe spring 36 is made of as great or greater strength than the springl6. Thus, the spring 36 will maintain the bridging bars 20 and 40normally in engagement with the shoulder 18a and the insulating disc 60respectively, i. e., their slidably mounted on said operator, said firstmaximum distance apart, and the spring IE will press the plunger M andspindle l8 integral therewith upwardly until the contact buttons on thebridging bar 20 are in engagement with the buttons on the terminals 30and 32. The spring 36 will then prevent any further upward movement ofthe plunger by the spring "5. However, when the plunger I4 is graspedand pulled, the force of spring 36 may be overcome and the bridging bar40 will be raised as the spring 36 is compressed until the contactbuttons on the bridging bar 40 engage with the contact buttons on thelower terminals and 52. On the other hand, when the plunger I4 isdepressed, the spindle l8 will carry the bridging bar 20 downwardly todisengage its contact buttons from the contact buttons of the upperterminals 30 and 32.

The plunger l8 and flanged collar 38 may be made of insulating material,whether or not bridging bars 20 and 40 are to be included in the same ordifferent circuits. However, if the bridging bars are to be included inthe same circuit, the spindle and flanged collar could be made of metalwithout interfering with the satisfactory operation of the device.

From the foregoing, it may be observed that in the central ormid-position, as illustrated in Figs. 2 and 3, a circuit may be normallyheld closed bythe engagement of the contacts of the bridging bar 20while the contacts of the upper terminals 30 and 32 and the circuit,including the lower terminals 50 and 52, will remain open. It theplunger I4 is pulled, this circuit may also be closed by reason of thecontacts on the bridging bar-40 engaging the contacts on theseterminals.

In many cases, it may be desirable to have all of the terminals in onecircuit in series. In that case, the circuit will only be completed whenthe plunger is pulled. Now, if the device is used in connection with anelectromagnetic switch, with the conventional holding contacts thereofin shunt with the terminals 50 and 52, then the electromagnetic switchwill stay closed after the plunger hasbeen pulledup and has been allowedI use of the device in a control circuit of an elec-' tromagneticswitch, said use being mentioned merely as an example and not as alimitation.

I claim:

1. In a momentary contact switch, a reciprocative operator adapted tonormally occupy a central position and to be moved to positions oneither side of said central position, a pair of fixed contacts, abridging contact slidably mounted on said operator, spring meansnormally holding said bridging contact in a certain position on saidoperator, other spring means normally urging said operator to hold saidbridging contact in engagement with said fixed contacts, a second pairof fixed contacts, a second bridging contact spring means normallyholding said second bridging contact in a certain position on saidoperator out of engagement with said second pair, the distance betweenthe contact surfaces of said first tral position and to be moved toalternate positions on either side of said central position, fixedcontact means, movable contact means non-rigidly mounted upon saidoperator and normally engaged with said fixed contact means,

means on said operator causing movement of said movable contact withsaid operator and disengagement of said fixed and movable contact meanswhen said operator is moved in one direction, and resilient means actingupon said movable contact means to hold it in engagement with said fixedcontact means but permitting movement of said operator in the otherdirection, in combination with second fixed contact means, and secondmovable contact means nonrigidly mounted on said operator the distancebetween said movable contact means being greater than the distancebetween said fixed contact means,

said resilient means normally holding the second movable contact meansdisengaged from the second fixed contact means, means on said operatorcausing movement with said operator of said second movable contact meansinto engagement with said second fixed contact means when saidoperator-is moved in said other direction, a hand grip for actuatingsaid operator in either direction, and means urging said operator tohold said first fixed and movable contact means engaged and said secondfixed and movable contact means disengaged in said normal centralposition.

3. In a momentary contact switch, a reciprocative operator adapted tonormally occupy a central position and to be moved to alternatepositions on either side of said central position, fixed contact means,movable contact means nonrigidly mounted upon said operator and normallyengaged with said fixed contact means, means on said operator causingmovement of said movable contact with said operator and disengagement ofsaid fixed and movable contact means when said operator is moved in onedirection, and resilient means maintaining contact pressure between saidfixed and movable contact means but permitting movement of said operatorin the other direction, in combination with second fixed contact means,and second movable contact means non-rigidly mounted on said operatorthe distance between said movable contact means being greater than thedistance between said fixed contact means, said resilient means normallyholding the second movable contact means disengaged from the secondfixed contact means, means on said operator causing movement with saidoperator of said second movable contact means into engagement with saidsecond fixed contact means when said operator is moved in said otherdirection, a hand grip for actuating said operator in either direction,and means urging said operator to hold said first fixed and movablecontact means engaged and said second fixed and movable contact meansdisengaged in said normal central position.

4. In a momentary contact switch, a reciprocative operator adapted tonormally occupy a central position and to be moved to altemate'positions on either side of said central position, fixed contact means,movable contact means en gageable and disengageable with said fixedcontact means, second fixed contact means, second movable contact meansengageable with and disengageable from the second fixed contact means,both said movable contact means being nonrigidly mounted upon andcarried by said operator, coil spring means oppositely urging said firstand second movable contact means into certain positions on saidoperator, means urging said operator in one direction and holding one ofsaid movable contact means in engagement with its fixed contact meansand the other of said movable contact means disengaged from its fixedcontact means, a hand grip for moving the operator in opposition to orin cooperation with said means-urging-said-operator to causesimultaneous momentary engagement of each movable contact means with itsfixed contact means or simultaneous disengagement.

DAVID W. JOHNSON.

